Multiple parties observing correlated data seek to recover each other's data and attain omniscience. To that end, they communicate interactively over a noiseless broadcast channel - each bit transmitted over this channel is received by all the parties. We give a universal interactive communication protocol, termed the recursive data exchange protocol (RDE), which attains omniscience for any sequen...
View full abstract»

In the private information retrieval (PIR) problem, a user wishes to retrieve, as efficiently as possible, one out of K messages from N non-communicating databases (each holds all K messages) while revealing nothing about the identity of the desired message index to any individual database. The information theoretic capacity of PIR is the maximum number of bits of desired information that can be p...
View full abstract»

We formulate a model for intermittent communication that can capture bursty transmissions or a sporadically available channel, where in either case the receiver does not know a priori when the transmissions will occur. Focusing on the point-to-point case, we develop a decoding structure, decoding from pattern detection, and its achievable rate for such communication scenarios. Decoding from patter...
View full abstract»

A new coding scheme for general N -node relay networks is presented for unicast, multicast, and broadcast. The proposed distributed decode-forward scheme combines and generalizes Marton coding for single-hop broadcast channels and the Cover-El Gamal partial decode-forward coding scheme for three-node relay channels. The key idea of the scheme is to precode all the codewords of the entire network a...
View full abstract»

The capacity region of the multicast Cognitive InterFerence Channel (CIFC) is investigated. This channel consists of two independent transmitters that wish to multicast two different messages, each to a different set of users. In addition, one of the transmitters-commonly referred to as the cognitive transmitter-has prior non-causal knowledge of both messages to be transmitted. This scenario subsu...
View full abstract»

We address the problem of finding the capacity of noisy networks with either independent point-to-point compound channels (CC) or arbitrarily varying channels (AVC). These channels model the presence of a Byzantine adversary, which controls a subset of links or nodes in the network. We derive equivalence results showing that these point-to-point channels with state can be replaced by noiseless bit...
View full abstract»

We investigate whether uncoded schemes are optimal for Gaussian sources on multiuser Gaussian channels. Particularly, we consider two problems: the first is to send correlated Gaussian sources on a Gaussian broadcast channel where each receiver is interested in reconstructing only one source component (or one specific linear function of the sources) under the mean squared error distortion measure;...
View full abstract»

The capacity-achieving input distribution of the discrete-time, additive white Gaussian noise (AWGN) channel with an amplitude constraint is discrete and seems difficult to characterize explicitly. A dual capacity expression is used to derive analytic capacity upper bounds for scalar and vector AWGN channels. The scalar bound improves on McKellips' bound and is within 0.1 bit of capacity for all s...
View full abstract»

This paper revisits the Gaussian degraded relay channel, where the link that carries information from the source to the destination is a physically degraded version of the link that carries information from the source to the relay. The source and the relay are subject to expected power constraints. The ε-capacity of the channel is characterized and it is strictly larger than the capacity fo...
View full abstract»

Suppose Yn is obtained by observing a uniform Bernoulli random vector Xn through a binary symmetric channel. Courtade and Kumar asked how large the mutual information between Yn and a Boolean function b(Xn) could be, and conjectured that the maximum is attained by a dictator function. An equivalent formulation of this conjecture is that dictator minimizes the predi...
View full abstract»

It was previously shown by Hashimoto that Forney's optimal erasure decoder can be significantly simplified, in the sense that a simplified decoder achieves the same random coding bounds, for the ensemble of independent and identically distributed codewords. In this paper, the analysis of simplified decoders is refined and generalized in several aspects. First, tighter random coding bounds for simp...
View full abstract»

We consider a binary energy harvesting communication channel with a finite-sized battery at the transmitter. In this model, the channel input is constrained by the available energy at each channel use, which is driven by an external energy harvesting process, the size of the battery, and the previous channel inputs. We consider an abstraction where energy is harvested in binary units and stored in...
View full abstract»

Guessing games for directed graphs were introduced by Riis for studying multiple unicast network coding problems. In a guessing game, the players toss generalised dice and can see some of the other outcomes depending on the structure of an underlying digraph. They later guess simultaneously the outcome of their own die. Their objective is to find a strategy, which maximizes the probability that th...
View full abstract»

This paper considers lossy source coding n-dimensional memoryless sources and shows an explicit approximation to the minimum source coding rate required sustain the probability of exceeding distortion d no greater than E, which is simpler than known dispersion-based approximations. Our approach takes inspiration in the celebrated classical result stating that the Shannon lower bound rate-distortio...
View full abstract»

In this paper, we consider the achievable sum-rate/distortion tradeoff for the Gaussian central estimation officer (CEO) problem with a scalar source having arbitrary memory. We describe how the arbitrary memory problem can be fully characterized by using known results for the vector CEO problem, and then we formulate the variational problem of minimizing the sum-rate subject to a distortion const...
View full abstract»

We introduce a new approach to proving that a sequence of deterministic linear codes achieves capacity on an erasure channel under maximum a posteriori decoding. Rather than relying on the precise structure of the codes, our method exploits code symmetry. In particular, the technique applies to any sequence of linear codes where the blocklengths are strictly increasing, the code rates converge, an...
View full abstract»

The Reed-Muller (RM) code, encoding n-variate degree-d polynomials over Fq for d <; q, with its evaluation on Fqn, has a relative distance 1 - d/q and can be list decoded from a 1- O(√d/q) fraction of errors. In this paper, for d ≪ q, we give a length-efficient puncturing of such codes, which (almost) retains the distance and list decodability prop...
View full abstract»

A long-standing conjecture of Golomb and Welch, raised in 1970, states that there is no perfect r error correcting Lee code of length n for n ≥ 3 and r > 1. In this paper, we study perfect codes in Zn under the l p metric, where 1 <; p <; ∞. We show some nonexistence results of linear perfect l p codes for p = 1 and 2 <; p <; ∞, r = 21/p, 31 View full abstract»

In this paper, we present a new method for explicitly constructing regular low-density parity-check (LDPC) codes based on Sn(Fq), the space of n × n symmetric matrices over Fq. Using this method, we obtain two classes of binary LDPC codes, C(n, q) and CT (n, q), both of which have grith 8. Then, both the minimum distance and the stopping distance of each class are investigated. It is shown ...
View full abstract»

In addition to their applications in data storage, communications systems, and consumer electronics, linear complementary dual (LCD) codes-a class of linear codes-have been employed in cryptography recently. LCD cyclic codes were referred to as reversible cyclic codes in the literature. The objective of this paper is to construct several families of reversible cyclic codes over finite fields and a...
View full abstract»

Generalized product codes (GPCs) are extensions of product codes (PCs), where code symbols are protected by two component codes but not necessarily arranged in a rectangular array. We consider a deterministic construction of GPCs (as opposed to randomized code ensembles) and analyze the asymptotic performance over the binary erasure channel under iterative decoding. Our code construction encompass...
View full abstract»

As an optimal combinatorial object, zero-difference balanced (ZDB) functions introduced by Ding in 2008, are a generalization of the well-known perfect nonlinear functions. ZDB functions have received much attention in recent years due to its important applications in coding theory and sequence design. One objective of this paper is to present a construction of ZDB functions based on a kind of gen...
View full abstract»

Caching is often used in content delivery networks as a mechanism for reducing network traffic. Recently, the technique of coded caching was introduced whereby coding in the caches and coded transmission signals from the central server were considered. Prior results in this area demonstrate that carefully designing the placement of content in the caches and designing appropriate coded delivery sig...
View full abstract»